Network Address Translation - technical definition

Allows an Internet Protocol (IP) network to translate public IP addresses into private ones. NAT, a popular technology for Internet connection sharing, is at times used in server load-balancing applications on networks in corporations. One of the most popular configurations is to have NAT map all the private IP addresses on a small local network to the single IP address assigned through an Internet Service Provider (ISP), thus allowing local systems to use a single Internet connection. In addition, NAT improves network security by preventing external computers from accessing the home network IP space. NAT intercepts both incoming and outgoing IP traffic and adjusts the addresses according to its translation rules.

NAT changes the source or destination address in the packet header (and adjusts the checksums) to perform the desired mapping. NAT performs either fixed or dynamic translations of one or more IP addresses. Typically, NATÂ’s functionality is implemented on routers and other gateway systems at the networkÂ’s boundary. MicrosoftÂ’s Internet Connection Sharing (ICS) adds NAT support to the Windows operating system.

See Also: Internet Protocol (IP); Internet Service Provider (ISP); IP Address.